1. Field of the Invention
This invention relates generally to a tracking device, and more particularly, to a device that triggers an alarm when a target person being monitored moves outside a predetermined range or when an unauthorized individual breaches that range. The invention is intended to prevent minors from being lost or kidnapped.
2. Description of the Background Art
It is well known that there is an epidemic problem today of people, especially minors, becoming missing, either by kidnapping or becoming lost. In many instances, minors could be protected from kidnapping or becoming lost if a cognizant individual were warned in a timely manner that the target minor moved outside a designated range or that an unauthorized individual came within a designated range of the target minor. Certain attempts have been made to develop reliable personal monitoring devices that address the foregoing issues. However, they have been unreliable or too expensive or complicated to mass-produce.
For instance, U.S. Pat. Nos. 4,593,273 and 4,675,656, issued to Narcisse, disclose an out-of-range personnel monitor and alarm that may be used by a convalescent home or the like to alert an attendant in the home that a supervised person has walked beyond a predetermined prescribed distance. The system discloses a base unit that transmits a signal to a mobile unit carried by the supervised person. The system includes an adjustable threshold circuit that produces a threshold signal whenever the signal received falls below the threshold. In response to the threshold output signal, a transmitter in the mobile unit produces an output signal to a receiver in the base, which in turn sounds an alarm. U.S. Pat. No. 4,785,291, issued to Hawthorne, discloses a distance monitor especially for child surveillance including an unmodulated radio frequency transmitter carried by a person to be monitored and receiver/monitor apparatus at a monitoring location for providing quantized visual and audible indicia based on received signal strength. The response levels are a function of the distance from the transmitter and receiver. Movement beyond a predetermined range is immediately detected and circuitry is provided to preset the maximum allowable range before an alarm is instituted. U.S. Pat. No. 5,289,163, issued to Perez, discloses a child position monitoring and locating device that monitors the position of a child by detecting signal strength of a radio frequency carrier from a transmitter attached to the child. When the signal is too weak, an adult is notified that the child is too far away by an audio tone or vibrations. The device has a locating display for indicating the child's relative position. U.S. Pat. No. 5,995,007, issued to Borja, discloses a monitoring system in a portable module including radio devices and an indicator for providing an indication upon the radio devices being separated by a predetermined amount.
Although the above noted art discloses various personal monitoring devices, they fail to adequately track missing persons, as contemplated by the instant invention. The instant invention addresses this unfulfilled need in the prior art by providing a personal monitoring device and system that tracks the movement of a predetermined target and provides warning signals when that target bypasses a predetermined perimeter.